Good Cholesterol Decreased in Males

To track the risk factors, researchers followed 507 Minneapolis school children from ages 11 to 19, when they had all reached sexual maturity. Fifty-seven percent of the children were male, 80 percent were Caucasian, and 20 percent were African American.

“We wanted to see which risks emerge first and how they relate to one another in normal, healthy school kids without diabetes or other major illnesses,” says Dr. Moran.

At age 11, boys and girls were similar in their body composition, lipid levels, and blood pressure, the researchers say.

Boys and girls became heavier during adolescence, increasing in body mass index and waist size. As expected during puberty, changes in body composition differed sharply between genders, with percentage of body fat decreasing in boys and increasing in girls.

During the study, changes in several cardiovascular risk factors or risk markers differed significantly between boys and girls:

Triglycerides (a type of fat in the blood) increased in males and decreased in females.

High-density lipoprotein (HDL or “good”) cholesterol decreased in males and increased in females.

Systolic blood pressure (the first number in the blood pressure reading, measuring the pressure when the heart contracts) increased in both, but significantly more in the males.

Insulin resistance, which had been lower in the boys at age 11, steadily increased until the young men at age 19 were more insulin resistant than the women.

Researchers found no gender difference in two other cardiovascular risk factors, total cholesterol, and low-density lipoprotein (LDL or “bad”) cholesterol.

“By age 19, the boys were at greater cardiovascular risk,” notes Dr. Moran. “This is particularly surprising because we usually think of body fat as associated with cardiovascular risk, and the increasing risk in boys happened at the time in normal development when they were gaining muscle mass and losing fat.”

Although girls gained cardiovascular protection when their proportion of body fat was increasing, excess fat is still a cause for concern.

“Obesity trumps all of the other factors and erases any gender-protective effect,” says Dr. Moran. “Obese boys and girls and men and women all have higher cardiovascular risk.”

Women's Hormones May Offer Protection

The researchers say further studies are needed to better understand the development of cardiovascular protection during adolescence.

“That the protection associated with female gender starts young is fascinating and something that we don’t understand very well,” explains Dr. Moran.

“That this protection emerges during puberty and disappears after menopause suggests that sex hormones give women a protective advantage,” he says.

“There’s still a lot that needs to be sorted out in future studies - estrogen may be protective or testosterone may be harmful,” says Dr. Moran.

Dr. Moran says that this is normal physiology and not something that is influenced by lifestyle factors.

Food Guide Offers Tips

The food guide pyramid can help you eat a variety of foods while encouraging the right amount of calories and fat.

The United States Department of Agriculture (USDA) and the US Department of Health and Human Services have prepared a food pyramid to guide you in selecting foods.

The food pyramid is divided into six colored bands representing the five food groups plus oils.

Orange represents grains: Make half the grains consumed each day whole grains.

Whole-grain foods include oatmeal, whole-wheat flour, whole cornmeal, brown rice, and whole-wheat bread. Check the food label on processed foods - the words “whole” or “whole grain” should be listed before the specific grain in the product.

Make most of your fat sources from fish, nuts, and vegetable oils. Limit solid fats like butter, stick margarine, shortening, and lard, as well as foods that contain these.

Blue represents milk: Get your calcium-rich foods. Milk and milk products contain calcium and vitamin D, both important ingredients in building and maintaining bone tissue. Use low-fat or fat-free milk after the age of two years.

However, during the first year of life, infants should be fed breast milk or iron-fortified formula.

Whole cow’s milk may be introduced after an infant’s first birthday, but lower-fat or skim milk should not be used until the child is at least two years old.